Contemporary telecommunications systems presently deployed, for example “public switched telephony network” (PSTN), mobile telephone and “Voice over Internet protocol” (VoIP), are substantially centralized in nature. They often employ central exchanges linked to users through trunk lines, local metro-rings and similar distribution structures. More recently, software-operated end-user devices have become available for connecting to such contemporary telephone systems, for example desk telephones, mobile telephones and VoIP devices. However, for performing almost any function offered by the telephony service provider, end-user devices are obliged to communicate with a central telephone exchange and/or branch exchange which executes one or more desired functions for them. In most cases, two end-user telephones of such a contemporary telephone system are not able to communicate directly to one another without a central exchange of the system linking the two end-user telephones together. For example, two people using their mobile telephones to converse together is facilitated by their two telephones communicating by radio via one or more mobile base stations, such base station communication being required even when the two people and their associated mobile telephones are in the same building. In another example, two people using “Voice over IP” software to converse together over the public Internet is facilitated by their software applications communicating via a central server, such server being required even though a connection can be established directly between the two people.
The use of centralized telephone systems places considerable demands on central switching exchanges. Such central exchanges are increasingly dependent on wide bandwidth optical connections employing dense wavelength division multiplexing (DWDM) with up to 120 optical channels distributed into wavelength bands of 50 GHz frequency spacing at an optical carrier frequency in the order of 300 THz. Such centralized exchanges are extremely costly and complex items of equipment which are susceptible to occasional malfunction, such malfunction potentially resulting in loss of communication traffic therethrough with potential corresponding compensation payments due to customers. Moreover, the cost of operating such central exchanges scales proportionally with the number of end users.
The inventors of the present invention have appreciated that such a centralized approach is sub-optimal in many situations and that advantages arise from the deployment of other alternative telephone system architectures.
In order to address issues arising from adoption of such alternative architectures, the inventors have devised the present invention.